Admit it. On more than one occasion you’ve tried to make equipment in your bindery department do something it isn’t designed to do. Judging from the many questions we get about various creasing, perforating, and cutting jobs, it seems to be a common intention. It often starts when a salesperson or customer comes in with a big job that’s easy to print but complex in the finishing.
We understand the temptation. “If we can just run a little bit heavier stock and add a couple of tools can we take this big job...” Or worse yet, the job is in production and now they’re trying to figure out how to finish it. In our bindery experience that’s often the norm rather than the exception!
Sometimes such questions about marginal print finishing jobs are easy to answer. If it won’t run through the machine in question, they simply have to find another way.
Since folding machines are often the machine in question, let’s look at their limitations. At the risk of over-simplifying, there are three general categories of folders, each with their own sets of limitations. The smaller the machine, the less flexibility you have in toying with maximums and minimums. Experienced bindery operators already know this, usually from a bad experience. The following guidelines should help the newcomer in deciding what’s feasible.
Small Desktop Folding Machines
With these machines the maximum and minimum specs are almost always set in stone. At the high end, a larger Martin-Yale machine will handle up to 110 lb index and even some semi-glossy stocks. A low end desktop letter folder handles 20# bond…that’s it.
There is usually no adjustment available on the fold rollers or fold plates. Machines are stamped out and riveted or glued together. There isn’t much room for getting creative with pulling things apart. You set the size and that’s it.
If you want to run something outside its limitations, go ahead. If it works, then consider it a bonus. Just don’t be disappointed if it doesn’t work.
The Baum 714 Category of Folding Machine
We used the Baum name because everyone will immediately know the type of machine we're talking about. These are production machines from several manufacturers that come with better friction or air feeders than desktop models. They’ll run a good range of coated or uncoated stocks. You can often score, perforate, or cut on these machines.
Maximum paper weight for the Baum is listed as 65 lb. cover/170gsm/7 pt. Faltex lists 40-250 gsm for suction feeders and 50-180 gsm for friction-fed machines. Morgana Major, an air-fed machine, takes 56-240 gsm.
Depending on the paper and the machine, you might be able to run a little lighter or a little heavier than listed, but you won’t get too far away from the listed limitations. You might have to make the paper do what you want but there are sometimes ways to do that.
Regarding the Baum 714 machines, we have introduced a new accessory package to make them even more versatile and productive. Check out our Baum 714 Ebook here, with information on available Tri-Creasers and Adjustable Shaft Kits.
Floor Model Folding Machines
Floor model folders are extremely versatile with regard to the range of papers they handle and accessories available including EZ Fit Tri-Creasers, Fast Fit Tri-Creasers and Micro Perforators to fit most popular makes and models. Depending on what model folder you have, limitations will vary. And most are not set in stone. The edge of the performance envelope can be explored and tested.
The maximum thickness, after folding, is generally in the .040-.060” range. If you’re not sure, set one of the fold roller calipers to your experimental thickness. Turn the machine over by hand. If you hear any scraping, you’ve exceed a very real limit.
For single folds, the “book” limit is probably around 10 pt./250 gsm or so. Practically speaking, on a bigger machine such as an MBO or Stahl 26”, you can probably get a 14 pt. paper to fold. It might take a little finessing, such as reducing the curl and using certain fold plates. On a smaller 20” machine with its smaller rollers, you’ll probably be limited to 10-12 pt.
For single sheet scoring or perforating, without subsequent folding, the book limit is probably around 12 pt or so. Practically speaking, we’ve been able to run and crease 18-20 pt stock, depending on density and grain direction. Again, this is on machines with the larger diameter fold rollers.
For right-angle folding in two directions (one fold in the parallel section, one fold in the right angle), the book limit is generally around 6-7 pt./150 gsm/60# cover. This limit is hard to exceed so if you’re near it, it’s a good idea to test. It’s very easy to get wrinkles at the head. You might also need to pre-score the first fold.
For right-angle folding in three directions such as 16-page signatures (one fold in the parallel, the second fold in a right angle, and the third fold in a second right angle), the limit is around 6 pt./125 gsm/100# text. In signature work you’ll want to perf the head and at the limit, you’ll definitely need the perf or else you get wrinkles. For brochure work of this sort, your limit will be lower in order to avoid wrinkling.
As you can see, limits can be exceeded as long as it’s done cautiously and with common sense. Of course if there are safety reasons for a particular limit, you never want to exceed it for obvious reasons.
Remember too that pushing limits will expose weaknesses in both machine and operator. Minor deficiencies will appear more readily at extremes. For instance if your rollers are slightly worn and you’re trying to run a 40# text, you’re more likely to get wrinkles or have register problems than you would with a 60# text.
In the end, there is something rewarding about pushing physical limits. We’re able to do something we couldn’t do before. The customer is happy. Our bosses might be happy. It adds a new dimension to our skill level and experience which ultimately makes us more valuable.
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